• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.6
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• pp.552-559
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• 2000

Most of the sensorless vector control methods use the equivalent circuit of induction motors. Therefore parameter auto-measurement of drive motor is essential function in commercial sensorless vector control inverters. The accuracy of motor parameter measurement greatly affects the performance of sensorless vector control. In this paper limitations of conventional measurement methods are examined, and new measurement methods are proposed to solve those limitations.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.287-292
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• 1998

This paper presents some results of performance evaluation test via actual machines of a new hybrid vector control utilizing a new indirect orientation scheme and stable filter embedded direct orientation scheme for induction motors without speed or position sensor. It is shown through the test by 0.3(kW) and 3.7(kW) motors that the proposed sensorless vector control has the following high potentialities: 1) speed range is 0 to 600(rad/s) or more, 2) zero-speed command is accepted and settles the machines at a stable standstill with no vibration 3) it can make machines to track variable command of acceleration and deceleration $\pm$6,000(rad/s2), 4) it can make machines to drive directly load of at least 26 times larger inertia than that of the machine, 5) it can make machines to produce much larger torque than the rating in torque control mode even at standstill. The performance confirmed by the test is far away for previous schemes or sensorless drive apparatuses.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.249-254
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• 1998

A control approach for the robust position control of induction motors based on the improved binary disturbance observer is described. The conventional binary disturbance observer is used to remove the chattering problem of a sliding mode disturbance observer. However, the steady state error may be existed in the conventional binary disturbance observer because it estimates external disturbance with a constant boundary layer. In order to overcome this problem, a new binary disturbance observer with an integral augmented switching hyperplane is improved. The robustness is achieved, and the continuous control is realised by employing the improved observer without the chattering problem and the steady state error. The effectiveness of the improved observer is confirmed by the comparative experimental results.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.106-113
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• 2014

Rotor eccentricity is one of the major factors that directly influence the security of horizontal electrical machines, and the critical speed of the shaft has a close relationship with vibration. This paper deals with the influence of thermal expansion on the rotor eccentricity and critical speed in large dry submersible motors. The dynamic eccentricity (where the rotor is still turning around the stator bore centre but not its own centre) and critical speed of a three-phase squirrel-cage submersible induction motor are calculated via hybrid analytical/finite element method. Then the influence of thermal expansion is investigated by simulation. It is predicted from the study that the thermal expansion of the rotor and stator gives rise to a significant air-gap length decrement and an inconspicuous slower critical speed. The results show that the thermal expansion should be considered as an impact factor when designing the air gap length.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.921-925
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• 1988

An attractive approach to speed of induction motors is to achieve full linearization via appropriate feedback. However, the prior results toward this direction are based on full feedback. In practice, rotor fluxes are not directly measurable but can be estimated using observers. We propose a nonlinear feedback controller with an observer. As t${\rightarrow}{\infty}$, the closed-loop system with our controller becomes as if it were a linearly decoupled system. We provide the stability analysis of our control method. Simulation and experimental results are also included to demonstrate the practical significance of our results.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.13-16
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• 2001

This paper describes the problems associated with the use of PWM ASDs to drive induction motors. A major effect of harmonic voltages and currents in induction motors is increased heating due to iron and copper losses at harmonic frequencies. The harmonic components thus affect the motor efficiency, and can also affect the torque developed. In order to investigate the effect of harmonics which is caused by using of nonlinear load at the low voltage system, we fixed up simple load model and measured the voltage and current. Measurement. results show that additional operation of linear load at the parallel bus in using nonlinear load such as ASD is helpful to the reduction of harmonic current.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2172-2174
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• 1998

In this paper, a speed estimation based on the quick torque control is proposed to realize speed sensorless control in a full range of induction motors. The proposed method can be formulated simply from a motor circuit equation and conducted easily by detecting primary motor currents and a voltage command at every sampling time. Since the method need not the differential values of primary currents in an arithmetic of a speed, it can be expected to improve the precision of speed estimation in a very low speed area, especially. Some numerical simulations were conducted with the assumption of using a Pulse Width Modulation voltage source inverter.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1218-1223
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• 2009

LIM(Linear induction motor)s are the main type of motors used for urban Maglev vehicles because they are less expensive to operate at a lower speed than linear synchronous motors. An LIM generates an attraction force while running, which perturbs the air gap of the electromagnet. This undesirable air gap variation could result in the mechanical contact of an electromagnet with the reaction plate. For this reason, the magnitude of the air gap variation must be limited within a certain range. The air gap changes when running the 1/2 vehicle under development for testing are analyzed through a test on the test track at KIMM. The results from this study could be used to minimize the air gap variations due to attraction force from LIM.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.312-314
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• 1997

In this paper, Computer Aided Optimum Design Technique for Three-Phase Induction Motors is proposed. In the technique, reference magnetic flux, specific electric loading factor, specific magnetic loading factor(magnetic flux density) and current density are adopted as design parameters, and minimum total cost including material cost and loss power cost is adopted as a objective function which has to satisfy output condition too. As a result of application to the existing motor, it is proved that this technique is very effective in view of gradually increasing energy costs.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.146-149
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• 2000

In this paper, Computer Colour Matching and Kitchen System (CCMKS) is developed on the basis of delphi package and one-chip processor with fuzzy-PID control. CCMKS will be widely used in the colour dyeing industry as an integrated colour matching and dispensing system which have more advantages than the conventional matching or dispensing system, when controlling the real dyeing processes. Delphi is utilized in making database and search/matching routes. The developed matching function reduces the search and matching time to about one third. One-chip processor is designed and manufactured for the distributed control of three-phase induction motors. Fuzzy-PID control is applied to the speed control of three-phase induction motors for a very precise weight of colour at CCMKS. The developed kitchen function decreases the dispensing time to about one twentieth. The experimental results show CCMKS has more excellent search time, more precise weight and much high fidelity than conventional colour matching or dispensing system, in the performance.